This is a two-part study of the use and costs of medical and support services of three groups of HIV-infected persons who do not have AIDS. The principal aims of the first and larger part of the study are (1) to provide detailed data on the use and costs of such services, by type of service, over a period of 12 months, of 65 HIV-infected persons registered on the University of California/San Francisco AIDS Registry who have a T- helper cell count under 200 but do not have AIDS; and to explore what patient characteristics, if any--age, time between first HIV-related medical visit and start in the study, employment status, and insurance status-affect the pattern of use and costs of these patients. The second and smaller part of the study compares the use of 11 participants in a Lentinan trial at San Francisco General Hospital with the use and costs of a group of 13 subjects on conventional treatment with a view toward estimating the costs of the additional services attributable to the drug trial per se. Data on the use and costs of all services are obtained directly from the providers of services, whose names and addresses are reported to us every two months until data for all participants have been obtained for 12 months.